He asked you to stay after class, because he has to talk to you

"Hey, I know that something is up, can you tell me what's bothering you? You don't have to tell me, but I want you to know that I care about you, and I'll always be there for you. I promise that anything you say will only stay with me, no one else"

(Art is made by Soartex07 on reddit. At least that's where I think it originally came from, I can't find it anywhere else so I'm sorry if they're not the original creator of the art)